Buccal mucosa location

Excellent accessibility to the buccal mucosa makes application of the dosage form painless, precisely located, and easily removable without discomfort at the end of the application period. The oral cavity consists of a pair of buccal mucosae. Thus, a drug-delivery system can be applied at various sites either on the same mucosa or, alternatively, on the left or right buccal mucosa on different applications. This is particularly advantageous if the delivery system contains a drug or excipient that mildly and reversibly damages or irritates the mucosa. 

The size of the delivery system varies with the type of formulation, i.e., a buccal tablet may be approximately 5-8 mm in diameter, whereas a flexible buccal patch may be as large as 10-15 cm in area. Mucoadhesive buccal patches with a surface area of 1-3 cm are most acceptable. It has been estimated that the total amount of drug that can be delivered across the buccal mucosa from a 2-cm system in 1 day is approximately 10-20 mg.f The shape of the delivery system may also vary, although for buccal drug administration, an ellipsoid shape appears to be most acceptable. The thickness of the delivery device is usually restricted to only a few millimeters. The location of the delivery device also needs to be considered. A mucoadhesive retentive system is preferred over a conventional dosage form. A bioadhesive buccal patch would appear to be the most appropriate delivery system because of its flexibility and the area of the buccal mucosa available for its application. The maximal duration of buccal drug retention and absorption is approximately 4-6 h because food and/or liquid intake may require removal of the delivery device. 

Located predominantly over the labial and buccal mucosae, these aphthae heal without scarring in 10-14 days. Recurrences are common. 

Basaloid squamous cell carcinoma (BSCC) is an uncommon, histologically distinct variant of SCC. In the upper aerodigestive tract, it occurs frequently in the base of the tongue, tonsils, hypopharynx, and larynx but has also been described in many other locations such as the palate, buccal mucosa, floor of mouth, nasopharynx, nasal cavity, and trachea. This is one of the subtypes of squamous carcinoma that can present with large neck node metastases and an unknown primary tumor. 

By studying the penetration of horseradish peroxidase across buccal mucosa, it was demonstrated that the permeation barrier is located in the upper one third to one quarter of the epithelium. After topical application, the horseradish peroxidase only permeated through the first 1-3 cell layers. However, when injected subepithelially it was found to permeate through as deep as the connective tissue and np as far as the MCGs zone. This is well correlated with the presence of the lipid-rich domain of the epithelium in its upper region. " The lipid composition in the buccal epithelium has a higher content of phospholipids, cholesterol esters, and glycosylceramides, while... 

With sublingual or buccal application, the drug encounters the nonkeratinized, multilayered squamous epithelium of the oral mucosa. Here, the cells establish punctate contacts with each other in the form of des-mosomes (not shown) however, these do not seal the intercellular clefts. Instead, the cells have the property of sequestering polar lipids that assemble into layers within the extracellular space (semicircular inset, center right). In this manner, a continuous phospholipid barrier arises also inside squamous epithelia, although at an extracellular location, unlike that of intestinal epithelia. A similar barrier principle operates in the multilayered keratinized squamous epithelium of the skin. 

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